When water is added to
the white powder it turns into
the familiar hydratedblue crystals.
Hydrated is pronounced
"high-dray-tid", it means
'with water'. This
colour change from white to blue
is used as a test for water.

If bluecopper(II) sulfate is heated,
an endothermicreaction
occurs and the blue crystals
lose their water.
The crystals turn white and become
anhydrouscopper(II) sulfate crystals
again. The reaction is reversible.Bluecopper(II)
sulfate crystals will also turn
white in the presence of concentrated sulfuric acid.

4) Dissolving some salts in water is
an endothermic process.Potassiumchloride and ammonium nitrate
both take in energy when they dissolve. If you put
a thermometer in the solution as they are dissolving,
you will see that the temperaturedecreases.